Local anaesthesia may be employed in hernia operations, either on its own or combined with general anaesthesia. The choice of technique will be influenced not only by local resources and skills, but also by patient preference. With a careful technique, local anaesthesia causes minimal physiological disturbance. This may be particularly useful for patients with cardiovascular or respiratory disease for whom there may be advantages in avoiding a general aesthetic. The absence of postoperative sedation or drowsiness allows early ambulation and diminishes the requirement for recovery facilities. Local anaesthesia provides postoperative analgesia for up to four hours and may be administered by the surgeon. When adrenaline is mixed with the local anaesthetic (normally in a dilution of 1:200,000) useful vasoconstriction is produced resulting in a relatively bloodless field.
The nerve supply to inguinal and femoral hernia comes from the anterior branches of the six lower intercostals nerves which continue forward on to the anterior abdominal wall accompanied by the last thoracic (subcostal) nerve. The iliohypogastric and ilioinguinal nerves (T12 and L1) supply the lower abdomen. They are blocked by an injection of local anaesthetic between internal and external oblique muscles just medial to the anterior superior iliac spine. The genitofemoral nerve (L1, 2) supplies inguinal cord structures and the anterior scrotum via its genital branch and supplies the skin and subcutaneous tissues of the femoral triangle via the femoral branch. Local anaesthetic agents are relatively free from side effects if they are administered in an appropriate dosage and in the correct anatomical location. However, systemic and localized toxic reactions may occur, usually from the accidental intravascular or intra-thecal injection, or the administration of an excessive dose of the local anaesthetic agent. Systemic reactions to local anaesthetics involve primarily the central nervous system and the cardiovascular system. The airway is maintained and oxygen administered by facemask, using artificial ventilation if apnoea occurs. Convulsions are treated with anticonvulsant drugs such as thiopentone or diazepam repeated as necessary. Profound hypotension and brady-arrhythmias should be treated with intravenous atropine and colloid or crystalloid infusions as plasma expanders may be necessary. Occasionally adrenaline may be required for severe hypotension or bradycardia. The invention provides a novel herbal local anaesthetic used in minor surgery like tooth removal or in topical surgery or in hernia operations without any toxic symptoms.